As of last week, the long gray line got longer still. Actually, there are two long gray lines: the proud one made up of graduates from the U.S. Military Academy at West Point, and the far more ignoble one made up of famous, powerful, middle-aged men who bring their lives and careers to ruin when they get caught dallying with women other than their wives. Gen. David Petraeus, whose just-revealed affair forced him to step down as Director of the Central Intelligence Agency, is the rare man who belongs to both.

In all the political and media froth that has been churned up since the scandal broke, one question that has been raised is the same one that always comes up at this point in these all-too familiar scandals: What the hell was he thinking? As recently as 1987 P.G. H. (pre-Gary Hart), politicians and other masters of the universe could get away with such randy antics pretty easily. But ever since Hart, who was on a glide path toward the 1988 Democratic presidential nomination, crashed and burned when he was caught having an affair, the game has changed. There’s no such thing as the discreet peccadillo anymore—not if a headline-hungry media has anything to say about it. And since the dawn of the Internet age, in which it’s impossible to hide your electronic footprints, the game has only gotten more dangerous. The fact that Petraeus, the nation’s former top spook, was tripped up by e-mail, is nothing short of jawdropping.

By now we’re familiar with all of the psychological and evolutionary explanations for this kind of sublime recklessness. Powerful men are natural risk-takers, type-A strivers; they’re naturally acquisitive — of power, wealth, and yes, sex. They’re charismatic egotists, and they’re often away from home for long stretches of time. All of this can be equally true of powerful women, of course, and yet they’re far less inclined to cheat. We know the familiar evolutionary answers for that too: Men, with their lifetime supply of sperm, are hardwired to mate repeatedly and indiscriminately. Women, who make a far higher investment in breeding, are more selective. What’s more, it’s anthropologically true if politically incorrect that while men, as a rule, are irresistibly attracted to youth and beauty, women can be made equally dizzy by power and the access to resources it implies. (If you doubt that, try this: Picture Donald Trump‘s wives. Now picture Donald Trump. Any questions?)

The tougher riddle — the one that’s never so well-answered — is why these men are so heedless of consequences. They define themselves by their status; they have typically worked a lifetime to acquire it and will fight like wildmen to keep it. And they know with virtual drop-dead certainty that they will lose it all if they step out of line. And then they go right ahead and step. Maybe that doesn’t matter to an independently wealthy man like Trump or a political Houdini like Bill Clinton. But most of the rest of them — Edwards and Spitzer and Weiner and Ensign and Sanford and the rest of the sorry queue — ought to be cautionary tales for anyone who comes later.

The explanation for the fact that that lesson so often doesn’t get learned may lie in the narcissism that can sit at the heart of power. Narcissism has been a badly overworked word of late — applied to all manner of selfish or preening behaviors that really don’t rise to the level of the true narcissistic personality disorder, which affects no more than 3% of the population. But that 3% is disproportionately represented among the ranks of the famous. What’s more, like all behavioral traits, narcissism can exist subclinically: you can have many of the dangerous traits of a narcissist without being a truly diagnosable case.

For both capital-N and lower-case narcissists, some of what may be going on is a sort of learned double-think. Of course powerful men are smart enough to be aware of consequences, but the charmed ride they’ve enjoyed for so long leads them to believe — viscerally if not rationally — that those rules somehow won’t apply to them. One of the reasons young, professional athletes so often get into trouble for DWI or domestic battery or weapons possession is that they truly have grown up outside of the rules — passing classes they never attend, graduating from fine colleges despite poor grades, receiving $10 million signing bonuses before throwing a pitch or taking a snap. For most famous men, the ride starts later but the lesson of invulnerability is just as powerfully learned.

“With leaders like this, there truly is no awareness of the likelihood that they’ll suffer any consequences,” says psychologist Amy Brunell of Ohio State University at Newark. “The idea is, ‘This doesn’t apply to me; somehow I’m not going to get caught.’ We’ve done studies about decision-making and impulsivity in narcissists and they really don’t think about the consequence.”

Psychologist Keith Campbell of the University of Georgia, who studies narcissists in relationships, has run similar experiments in which subjects play games of luck or skill and wager imaginary money on the results. A great deal about how aggressively they play seems to be linked to how high they score on questionnaires that measure narcissism. “On risk-taking and betting tests, narcissists tend to overpredict their performance,” Campbell says. “And they tend not to learn from the times they don’t win.”

A certain psychic drunkenness may also come into play. Narcissists are hooked on public adoration — from crowds, from interns, or, in Petraeus’s case, from hagiographic biographers. There’s a driving-while-impaired quality to their decision-making powers when they’re on this kind of high, and their judgment just flies out the window. “This need for getting adored creates a myopia,” says psychologist Aaron Pincus of Penn State University. “They’re not thinking in the long term. So if the intern makes her self available in the Oval Office right now, that’s all I’m thinking about.”

Adds Campbell: “It’s not that guys like Tiger Woods are aliens. They’re like anyone else, but they have stronger needs for ego enhancement and validation. Throw in overconfidence and a habit of walking on people and you get self destructive behavior. It bites you in the ass over time.”

In some cases, once-bitten does not mean twice shy, but those cases are rare. Clinton was serially caught and serially wriggled free. But even he, to all appearances, at last fell into line after 1998, though the calming effects of age—to say nothing of his bouts with heart disease—may have played a role too. But other men get just a single strike. Petraeus, Edwards, Spitzer and the rest would surely like to turn back the clock, but barring a longshot bid at redemption (certainly impossible in Edwards’ case), the public is probably done with them.

There would, perhaps, be something good in all this if the tragedy of these men served as teachable moments for others — and the fact is they probably do. You can’t prove a negative, and we can never know of the career-wrecking affairs that didn’t take place because successful men looked at the narcissistically fallen and made a sharp turn in the other direction . But there are more than enough — as we repeatedly learn — who who plow straight ahead, and there probably always will be. David Petraeus, the latest in a very long line, is highly unlikely to be the last.